<p>The first control is to displace the primary piston 40 by the amount obtained by multiplying the input rod 7 displacement quantity by a proportional gain. The second control is to propel the primary piston 40 by a prescribed offset thereby executing the first control. The third control is to displace the primary piston 40 by the amount obtained by multiplying the input rod 7 displacement quantity by a proportional gain specifically at a pressure decrease request. The brake force control device 2 properly selects a control method from the first to third control methods to control the primary piston 40 based on the automatic braking release conditions and a driver's brake request when a driver executes a brake operation during the automatic braking.</p>
